Sprinkler systems are among the most useful tools firefighting. Today’s systems have been shown to reduce deaths and property loss by more than 65 percent. Fire sprinklers work because high heat triggers the sprinkler system. When a blaze ignites, the air directly above it heats rapidly. This hot air rises and spreads along the ceiling. When the air is hot enough and reaches a sprinkler head, it triggers a chain reaction. It’s important for water in a fire sprinkler system to be pressurized. This allows the water to spray outward in an arc to more thoroughly douse the fire and prevent it from reigniting.